“University of Hong Kong scientists claim to have the first evidence of someone being reinfected with the virus that causes Covid-19. A 33-year-old man returning to Hong Kong from a trip to Spain in mid-August was tested positive for novel coronavirus for second time in August. The man, who had earlier tested positive for novel coronavirus in March, had recovered then from the disease. “This is the first case we have found of reinfection and I believe, probably, there are more such cases,” Dr Kelvin Kai-Wang To, the microbiologist who led the work, told India Today. Are people who have had Covid-19 immune to new infections and for how long?